XO (unexploded ordnance) are live bombs which failed to explode on impact. Most of the UXO in Laos resulted from cluster bombs which split apart mid-air to scatter 100s of cluster bomb units (CBUs). CBUs are also called cluster bomblets or “bombies.”
From 1964 until 1973, the Air Force dropped 288 million bombies on Laos, primarily in the mountainous Xieng Khouang province 100 miles north of the capital, Vientiane. Approximately 30% of the bombies failed to explode when they landed in rice fields, streams, bamboo groves and the like. Thus, there were more than 80 million bombies littering the Lao countryside. Those bombies killed or maimed 300 farmers and children as recently as 2011.
International teams have spent tens of millions of dollars annually to deactivate UXO in Laos for the past 18 years. At this rate of cleanup, it will take more than 2,000 years before the countryside of Laos is rid of UXO.